Present seat suspension systems for various work machines or the like typically include suspension arrangements for springing and damping movements incurred when forces are exerted on the seat during operation of the work machine. Although the damping movements may improve operator comfort, these systems generally operate to move the seat in a vertical direction which may cause the distance between the operator and any foot-controlled pedals to change throughout the operation of the machine. The changing distance between the seat and the foot-controlled pedals force the operator to compensate by shifting positions within the seat or varying the pressure on the foot-controlled pedals.
A design disclosed in U.S. Pat. No. 3,853,296 issued to Carl Fredrik Johan Sigvard Forssell on Dec. 10, 1974 utilizes a vehicle seat suspension with a pair of links arranged on opposite sides of a vehicle seat bottom. The separate links of each pair intersect each other and are joined together at their point of intersection. One link in each pair of links is firmly connected to the corresponding link of the opposite pair and is pivotally joined at its ends to the seat bottom and to a supporting portion. The other link arm is pivotally joined to any one of its three points of attachment and is both pivotally and displaceably arranged at the other two points of attachment. The rear end of the former pivotally connected link has a portion which is angled upwardly and the rear pivot point of the link lies within this portion so that the front and rear pivot points are roughly on the same level in the normal height position of the seat. This seat suspension system is designed to absorb large forces in a horizontal direction without risk of breaking under buckling stresses and which does not move appreciably in a horizontal direction during spring movement. This is accomplished due to the use of a pivotably journalled link arm which is longer than the other link arm and arranged so that both its ends lie outside the ends of the other link arm when viewed sideways of the seat. Although this system utilizes a scissor-type suspension system, the damping of the forces on the seat are still corrected in substantially a vertical direction changing the distance between the seat and the operator's foot-controlled pedals due, in part to the positions of the pivot points and methods of attachment.
The present invention is directed to overcoming the problems as set forth above.